Method and device for determining the hardness of products such as fruit

In a method for determining the hardness of a product, for instance fruit, during a measuring cycle, comprising: supporting the product, tapping the product with a tapping device at least one position of the product, as a result of which the product as a whole is set in its natural vibration and produces vibration signals, sensing the vibration signals with a signal sensor, and processing the vibration signals with a signal processing device, in which the hardness FRi of the product is determined, and further comprising: sensing the signals produced by the tapping device with a second signal sensor, processing the vibration signals with a second signal processing device, the elastic properties of the product being determined in a volume range around the above at least one position, determining the hardness FIi of the product, comparing FIi and FRi and checking the comparison with a pre-adjusted value, the tapping and sensing with the second signal sensor being repeated when the comparison does not satisfy the pre-adjusted value, the hardness can be advantageously determined, in particular intended for labeling products when selecting and subsequently sorting fruit. A device for carrying out this method can be used both for desk-top applications and for on-line determinations on sorting machines.